He was present when the Pillar of Autumn was boarded by units of the Covenant Navy during the opening phases of the Battle of Installation 04. He successfully escaped the ship, that later crash landed in a desert on the ring. Presumably, he was part of the attack that took Alpha Base.

He was one of the Marines in charge during the airborne assault on the Silent Cartographer. Waller was in command of the beachhead LZ secured by Master Chief. He and his Marines came under attack twice as Covenant forces attempted to retake the LZ, however they beat back both assaults.

When Foehammer spotted a third Covenant attack coming from two Covenant dropships, Waller knew his squad was probably unable to hold them off and radioed the Master Chief to hurry and locate the Cartographer. The Covenant assault quickly overwhelmed Waller and the remaining Marines at the beachhead LZ, killing them all.